DE60301617T2 - POLYMER FILM - Google Patents

Abstract

A film with a broad molecular weight distribution, excellent impact strength and a high dart drop value or moderate dart drop value accompanied by good optical property consisting of a bimodal terpolymer comprising a low molecular weight homopolymer of ethylene and a high molecular weight terpolymer of ethylene, 1-butene and a C6 to C12 a-olefin, or a bimodal terpolymer comprising a low molecular weight polymer which is a binary copolymer of ethylene and a C4 to C12 a-olefin and a high molecular weight polymer which is either a binary copolymer of ethylene and 1-butene, if the low molecular weight polymer is a binary copolymer of ethylene and a C6 to C12 a-olefin, or a terpolymer of ethylene, 1-butene and a C6 to C12 a-olefin.

Description

The The invention relates to polyethylene films or films, in particular heat-sealing films e.g. For the use in the packaging of products.

films of polyethylene (PE), in particular of linear polyethylene lower Density (LLDPE), are in large Scope for the packaging of products, e.g. Food, liquids (e.g., refills of detergents) and so on. In this use, the welding properties the film is particularly important. For this it is known to enter the PE Introduce comonomer, in the polymer, a component with a lower melting point to provide and thus the hot tack property of the Improve film. In this context, it is known that the introduction of a Witch-ethylene copolymer in LLDPE gives the LLDPE excellent welding properties, the contains a butene-ethylene copolymer, and that this Introduce of an octene-ethylene copolymer gives LLDPE excellent properties which contains a hexene-ethylene copolymer.

The use of higher α-olefin comonomer, C ₄ ie - or higher α-olefins, however increases the cost of the polymer product, and the efficiency in the introduction of the comonomer generally decreases when the carbon content increases the comonomer, ie hexene introduced less effectively than butene, and octene is introduced less effectively than witches, etc.

We have now surprisingly found that through the introduction of two different α-olefin comonomers a polyethylene film product can be made which is superior to the Polyethylene has excellent welding properties, the made with each of the comonomers as the sole comonomer are.

Accordingly, in one aspect, the invention provides a film of polyethylene prepared by a polymerization catalyzed by a single site catalyst having more than one η ⁵ -cyclic ligand, and which as comonomers for ethylene at least two C _4-12 α-olefins, preferably at least two α-olefins, which are selected from butene-1, hexene-1, 4-methylpentene-1, heptene-1, octene-1 and decene-1, in particular butene-1 and witches 1, are selected.

The inventive films are for the use as heat-sealing foils particularly suitable; e.g. co-extruded laminates with five or more seven layers, e.g. For the use in food packaging and medical Packagings. You can also for the FFS (mold filling and welding) used in the industry, being a combination of welding and mechanical Properties is important.

In many cases becomes the weld, which is generated between the film and the object to be welded, charged when it is still warm. This means that the hot tack properties the sealing layer are critical, so even before cooling the Formation of a firm weld is secured. All heat seal foils have a window in which welding can take place, i. in which the sealing layer is partially melted. This welding window was pretty tight, which means that the temperature control at Heat sealing process is critical. The films of the invention enable a wider welding window, so that welding processes can take place at a lower temperature and is secured, that the temperature control during heat sealing has less meaning. When worked at a lower temperature will the advantages be that the to be welded Subject is not exposed to high temperature and the others Layers of film that are not involved in welding, also none be exposed to high temperature. There are also economic Advantages, since lower temperatures of course produce cheaper and keep up.

The polyethylene of the film according to the invention is typically a mixture of two or more polyethylenes, for example produced by mixing or polymerization reactions in two or more stages. The components of the polyethylenes may be homopolymers, copolymers, terpolymers or polymers of four or more comonomers; however, preferably at least one polymer is a terpolymer, or at least two polymers are copolymers, wherein in particular one monomer, the major component, is ethylene, and one or two comonomers, the minor components, are C ₄ and / or C ₆ alpha-olefins , It is particularly preferred that the polymer be produced in a two or more stage polymerization, wherein at a previous stage the lower alpha-olefin comonomer is introduced and at a later stage the higher alpha-olefin comonomer is introduced. Nevertheless, it is within the scope of this invention to produce the polymer in a two-stage polymerization reaction, wherein in the first stage an ethylene homopolymer and in the second stage an ethylene terpolymer is produced or vice versa, or wherein in the first stage an ethylene copolymer is produced with the higher alpha-olefin comonomer and in the second stage an ethylene copolymer is formed with the lower alpha-olefin comonomer. Similarly, an ethylene copolymer in the first stage and an ethylene terpolymer in the second stage can be produced and vice versa.

Of the As used herein, the term "homopolymer" is ethylene for a Polyethylene which is substantially, i. at least 98% by weight, preferably at least 99% by weight, more preferably at least 99.5 Wt .-%, particularly preferably at least 99.8 wt .-%, of ethylene consists.

The ethylene polymers of the polymer film of the present invention are made with a so-called uniform active catalyst catalyst comprising a metal to which more than one η ⁵ cyclic ligating ligand is coordinately attached. Such η-bonded metals are normally referred to as metallocenes and the metals are typically Zr, Hf or Ti, especially Zr or Hf. The η-bonding ligand is an η ⁵ -cyclic ligand, ie a homo- or heterocyclic cyclopentadienyl group, optionally with condensed or bonded substituents. Such metallocene catalysts have been extensively described in the scientific literature and patent literature for about twenty years. Such metallocene catalysts are often used with activators for the catalyst or cocatalysts, for example alumoxanes, such as methylaluminoxane, which in turn are just as extensively described in the literature.

The in the film of the invention The polymer used is preferably bimodal or multimodal, i. the curve of its molecular weight comprises as a result of the fact that this Polymer comprises two or more separately produced components, none single peak but instead the combination of two or more peaks (which can be distinguished or not), whose Middle at different average molecular weights lies. In this embodiment corresponds to a higher molecular weight component preferably a copolymer (or terpolymer, etc.) of the higher alpha-olefin comonomer, and a lower molecular weight component preferably corresponds an ethylene homopolymer or copolymer (or terpolymer, etc.) of the lower α-olefin comonomer. Such bimodal ethylene polymers may be e.g. through a two-stage or multi-stage polymerization or by the use of two or more different polymerization catalysts in a polymerization step be generated. However, they are preferably in a two-stage Polymerization wherein the same catalyst, e.g. a metallocene catalyst is used, in particular in a suspension polymerization in a closed loop reactor, followed by gas phase polymerization in a gas phase reactor. A system of reactor with closed Circle - gas phase reactor is from Borealis A / S, Denmark sold as BORSTAR reactor system.

The low molecular weight polymer fraction is preferably produced in a continuous loop reactor in which ethylene is polymerized in the presence of a polymerization catalyst as noted above and a chain transfer agent such as hydrogen. The diluent is typically an inert aliphatic hydrocarbon, preferably isobutane or propane. A comonomer of a C ₄ -C ₁₂ α-olefin is preferably added to control the density of the low molecular weight copolymer fraction.

The Hydrogen concentration is preferably selected so that the proportion from the low molecular weight copolymer has the desired melt flow rate. Stronger Preferably, the molar ratio between hydrogen and ethylene at 0.1 to 1.5 mol / kmol, especially preferably at 0.2 to 1.0 mol / kmol.

If the density of the low molecular weight copolymer fraction to be achieved exceeds 955 kg / m ³ , it is advantageous to operate the closed loop reactor using the diluent propane under so-called supercritical conditions where the operating temperature is the critical temperature of the Reaction mixture exceeds and the operating pressure exceeds the critical pressure of the reaction mixture. A preferred temperature range is then 90 to 110 ° C, and the range of pressure is 50 to 80 bar.

The suspension is discontinuously or continuously removed from the closed loop reactor and transferred to a separation plant where at least the chain transfer agent (eg, hydrogen) is separated from the polymer. The polymer containing the active catalyst is then introduced into a gas phase reactor in which the polymerization takes place in the presence of further ethylene, further comonomer (further comonomers) and optionally further chain transfer agent, whereby the Part of the high molecular weight copolymer is produced. The polymer is withdrawn discontinuously or continuously from the gas phase reactor and the remaining hydrocarbons are separated from the polymer. The polymer collected from the gas phase reactor is the bimodal terpolymer.

The Conditions in the gas phase reactor are chosen so that the ethylene polymer has the desired properties Has. Preferably, the temperature in the reactor is between 70 and 100 ° C and the pressure at 10 to 40 bar. The molar ratio between hydrogen and ethylene is preferably in the range of 0 to 1 mol / kmol, stronger preferably from 0 to 0.5 mol / kmol, and the molar ratio between the α-olefin comonomer and Ethylene is preferably in the range of 1 to 100 mol / kmol, more preferably from 5 to 50 mol / kmol and more preferably from 5 to 30 mol / mol.

The inventive film can be done using conventional Process for the production of films are produced. The foil typically has a thickness of 10 to 1000 microns, especially from 20 to 100 microns. The particular Thickness will be according to the type of product that comes with this film should be packaged, and the expected subsequent treatment conditions selected.

The However, films are preferably extruded, more preferably with an inflation ratio of 2: 1 to 4: 1.

If he wishes, For example, the film may be multilayer, e.g. as a result of lamination or coextrusion.

at a multilayer film can the other layers comprise any film grade polymer resin, the desired ones Properties and the desired Has processability. Examples of such polymers include: PA (Polyamide) and EVA for a barrier layer; polar copolymers of ethylene, such as copolymers of ethylene and vinyl alcohol or copolymers of ethylene and a acrylate monomer; Adhesive layers, e.g. Ionomers, copolymers of ethylene and ethyl acrylate, etc .; HDPE for rigidity; LDPE resins in one High pressure process have been produced; LLDPE resins produced by the polymerization of Ethylene and α-olefin comonomers in the presence of a Ziegler, chromium or metallocene catalyst have been generated; and MDPE resins. The multilayer film has but preferably at least one sealing layer, preferably one Outer layer which is a bimodal ethylene polymer containing at least two other alpha-olefin comonomers contains.

In another aspect, the invention also provides a polyethylene composition for film production, the composition comprising a polyethylene prepared by polymerization catalyzed by a single site catalyst having more than one η ⁵ -cyclic ligand , and which comprises as comonomers for ethylene at least two C _4-12 -α-olefins, preferably at least two α-olefins, selected from butene-1, hexene-1, 4-methylpentene-1, heptene-1, octene-1 and Decene-1, in particular butene-1 and hexene-1, are selected.

In another aspect, the invention provides a product (eg, food, a liquid such as a detergent, etc.) packaged in a heat-sealable film of a polyethylene produced by polymerization catalyzing a single-site catalyst which has more than one η5-cyclic ligand and which comprises as comonomers for ethylene at least two C _4-12 -α-olefins, preferably at least two α-olefins, which are butene-1, hexene-1, 4-methylpentene 1, heptene-1, octene-1 and decene-1, especially butene-1 and hexene-1.

• a) ein Ethylenhomopolymer mit geringem Molekulargewicht und
• b) ein Terpolymer mit hohem Molekulargewicht von Ethylen, 1-Buten und einem C₆-C₁₂-α-Olefin,

oder bimodales Polymer, welches umfaßt

• a) ein Polymer mit geringem Molekulargewicht, das ein binäres Copolymer von Ethylen und einem C₄-C₁₂-α-Olefin ist, und
• b) ein Polymer mit hohem Molekulargewicht, das entweder ein binäres Copolymer von Ethylen und 1-Buten ist, wenn das Polymer mit geringem Molekulargewicht von a) ein binäres Copolymer von Ethylen und einem C₆-C₁₂-α-Olefin ist, oder ein Terpolymer von Ethylen, 1-Buten und einem C₆-C₁₂-α-Olefin.

The film of the invention preferably comprises any bimodal terpolymer comprising:

• a) a low molecular weight ethylene homopolymer and
• b) a high molecular weight terpolymer of ethylene, 1-butene and a C ₆ -C ₁₂ α-olefin,

or bimodal polymer comprising

• a) a low molecular weight polymer which is a binary copolymer of ethylene and a C ₄ -C ₁₂ α-olefin, and
• b) a high molecular weight polymer which is either a binary copolymer of ethylene and 1-butene when the low molecular weight polymer of a) is a binary copolymer of ethylene and a C ₆ -C ₁₂ α-olefin terpolymer of ethylene, 1-butene and a C ₆ -C ₁₂ -α-olefin.

In a preferred embodiment, the present invention provides a film of a bimodal polymer having a relatively narrow molecular weight distribution (MWD) and excellent weldability properties, good processibility, low permeability, and low extractables. The MWD is preferably 2.5 to 10, especially 3.0 to 8.0.

Of the Term modality a polymer stands for the shape of the curve of its molecular weight distribution (MWD), i. the appearance of the curve of the polymer weight fraction as a function of its Molecular weight. When the polymer is in a sequential process Steps, i. using series connected reactors and using different conditions in each reactor, has been produced in various reactors different polymer content each having its own molecular weight distribution, which is considerable can differ from the others.

The Curve of the molecular weight distribution of the resulting final polymer can as overlay considered the curve of the molecular weight distribution of the polymer components which consequently has two or more different maxima or in comparison with the curves of the individual shares at least is significantly wider. A polymer that has such a molecular weight distribution curve shows is called bimodal or multimodal.

multimodal, especially bimodal polymers are prepared by various methods, e.g. in EP-0 517,868 B1 or WO-A-96/18662.

The multimodal polyethylene is preferably in a multistage Process produced in a multi-step reaction sequence, such as it is described in EP-0 517 868 B1 and WO-A-96/18662. The content These documents are mentioned here for reference.

at In this process, ethylene is used in a first step in a reactor with a closed circle in the liquid phase of an inert low-boiling hydrocarbon medium polymerized. Then that will be Reaction mixture discharged from the closed loop reactor, and at least the inert hydrocarbon medium is from the reaction mixture removed, and the polymers are in one or more gas phase reactors promoted in which the polymerization in the presence of gaseous ethylene will continue. The multimodal generated by this method Polymer has excellent homogeneity in distribution the different polymer proportions, e.g. with a polymer mixture can not be achieved.

Of the Catalyst for the preparation of this ethylene polymer may be a catalyst with uniform active centers, such as one of the catalysts, which are disclosed in WO 97/28170, WO 00/34341 and WO 00/40620. The content of these publications is mentioned here as reference.

The bimodal polymer composition preferably comprises a low molecular weight copolymer fraction and a high molecular weight copolymer fraction. The proportion of the low molecular weight copolymer, provided that a binary copolymer is used, contains a C ₄ -C ₁₂ α-olefin, especially one selected from the group of 1-butene, 1-hexene, 4-methyl-1 pentene, 1-octene and 1-decene is selected. The C ₆ -C ₁₂ α-olefin of the high molecular weight copolymer portion is preferably selected from the group of 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and 1-decene.

The Weight average molecular weight of the bimodal polymer is preferably between 50,000 and 250,000 g / mol. The share from the Low molecular weight polymer preferably has a weight average the molecular weight of preferably 5,000 to 100,000 g / mol, stronger preferably from 10,000 to 70,000 g / mol, and the proportion of the polymer high molecular weight preferably has a weight average of Molecular weight of preferably 50,000 to 500,000 g / mol, more preferably from 100,000 to 300,000 g / mol.

The Molecular weight distribution of the polymer is further determined by its Melt flow rate (MFR) according to ISO 1133 at 190 ° C characterized. The melt flow rate depends primarily on the average Molecular weight off. The reason is that larger molecules give the material a lower tendency to flow lend as smaller molecules.

An increase in molecular weight means a decrease in the MFR value. The melt flow rate is measured in g / 10 mm of polymer output under certain conditions of temperature and pressure and is a feature of the viscosity of the polymer which, in turn, for each type of polymer is mainly influenced by its molecular weight distribution, but also its degree of branching and so on. The enamel flow rate measured at a load of 2.16 kg (ISO 1133) is referred to as MFR ₂ . The melt flow rate measured at 21.6 kg is again referred to as MFR ₂₁ .

The final bimodal polymer preferably has a melt flow rate MFR ₂ of 0.3 to 5 g / 10 min, more preferably 0.4 g / 10 min. The content of the low molecular weight polymer preferably has a melt flow rate MFR ₂ of 50 to 1,000 g / 10 min, more preferably 50 to 300 g / 10 min.

The Melt flow rate and the density of the material are for the strength properties whereas the density is decisive only for the melting point, the surface hardness, the permeability and water absorption is crucial.

The density of the final bimodal polymer is preferably 905 to 940 kg / m ³ , more preferably 905 to 930 kg / m ³ . The density of the low molecular weight polymer portion is preferably 925 to 945 kg / m ³ , more preferably 925 to 940 kg / m ³ .

The bimodals according to the invention Polymer includes preferably 30 to 70, stronger preferably 35 to 60 and more preferably 38 to 55 wt .-% of Part of the low molecular weight copolymer, namely based on the total composition.

Of the total comonomer content in the polymer is preferably 0.1 to 10 Mol%, preferably 0.5 to 7 mol%, and in the polymer with low Molecular weight is the comonomer content is preferably 0 to 3.0 mol%, preferably 0 to 2.5 mol%. In the high molecular weight polymer is the comonomer content preferably 0.1 to 10 mol%, preferably 0.1 to 7 mol%. Of the Comonomer content can be measured by NMR.

The Molecular weight of the high molecular weight copolymer fraction should also be such that the final bimodal polymer, the melt index explained above and the explained above Has density when the proportion of the low molecular weight copolymer the above melt index and the above Has density.

In addition to Polymer itself can the composition and the film according to the invention also antioxidants, Process stabilizers, pigments and other additives known in the art. The bimodal SSC ethylene polymer with two other alpha-olefin comonomers can also be used with other polymers be mixed, the welding properties and mechanical Properties obtained for the desired end use of the polymer film are suitable. Examples of such other polymers used can be belong LDPE, HDPE, MDPE, LLDPE, EMA, EBA and EVA. Typically, many can more polymers account for up to about 50% by weight of the total polymer, in the case of HDPE, MDPE or LLDPE, more preferably up to 30% by weight. This intake of LDPE is clear given the achievable Improvement of the optical properties of the film particularly advantageous.

When films are to be used for packaging certain products, especially foods, it is particularly important that the film has high clarity and gloss. When films are made only from SSC polymers (ie, polymers made with uniform site catalysts), their appearance is often relatively hazy and / or dull. This can be remedied by blending an LDPE into the SSC polyethylene such that the LDPE is, for example, up to 5 weight percent, more preferably 1 to 5 weight percent, more preferably 3 to 4 weight percent, most preferably about 3 , 5 wt .-% of the polymer mixture. We have also surprisingly found that in this context LDPE having a relatively high density, eg 925 to 932 kg / m ³ , is particularly effective. An example of such an LDPE is commercially available from Borealis A / S under the trade name Himod LDPE, which is produced by high pressure tube processes.

This effect of relatively high density LDPE on the optical properties of the PE film is quite unexpected, since it has been expected that the higher the density of the LDPE additive, the lower the improvement in optical properties would be. Thus, according to another aspect, the invention provides the use of relatively high density LDPE, eg having a density of 925 to 932 kg / m ³ , as an additive in a polyethylene composition (eg as 1 to 5% by weight of the composition) for the Film production to improve the optical properties of the film produced therefrom.

Examples of stabilizers are hindered phenols, hindered amines, phosphates, phosphates and Phosphonites.

Examples of pigments are carbon black, Ultramarine blue and titanium dioxide.

Examples further additives are e.g. Clay, talc, calcium carbonate, calcium stearate, zinc stearate and antistatic additives, such as those sold under the trade name Lankrostat.

The present invention will now be elucidated with reference to the following non-limiting examples and the attached drawing, wherein the 1 Figure 4 is a graph of hot tack versus temperature for films blown from the polymers of Example 2 and four comparative polymers.

hot tack:

"Hot tack" is a procedure for measuring the strength of the heat seal of the film and the Laminating immediately after the welding process. These properties comes with an international DTC hot tack tester, model 52-D, w-4236.

The Samples are cut to a width of 15 mm. The welding time is 0.5 s, the delay time is 0.1 s, and the welding pressure is 90 N. Welding is measured at different temperatures, and at each Test temperature will be five taken in parallel. These samples are conditioned before the test Have been at least 24 hours at ambient temperature were left standing.

MFR

The MFR was measured according to ISO 1133 at 190 ° C. The load is given as a footnote, ie MFR ₂ stands for the measurement made at a load of 2.16 kg, or MFR ₂₁ stands for the measurement made at a load of 21.6 kg.

FRR

The ratio of flow rates (FRR) is the ratio of two melt flow rates measured at different loads. The loads are given as a footnote. Thus, FRR _21/2 denotes the ratio between MFR ₂₁ and MFR ₂ .

MWD:

The weight average molecular weight M _w and the molecular weight distribution (MWD = M _w / M _n , where M _{n is} the number average molecular weight) are measured by a method based on ISO / TC61 / SC5 N 5024. The main difference between this method and the method used is the temperature; the ISO process is carried out at room temperature, whereas the process used is done at 140 ° C. The relationship between M _w and M _n is a feature of the width of the distribution, as each is affected by the opposite end of the "population".

Density:

The Density is in accordance with ISO 1183 / D measured.

Extractable in hexane ingredients:

The Hexane extractions were performed using ASTM D5227.

Oxygen permeability:

The Oxygen permeability is performed using ASTM D3985.

Water permeability:

Of the Water vapor transmission rate is in accordance with ASTM F1249 measured.

rheology:

The rheological properties of the polymers were measured with the Rheometrics RDA II dynamic rheometer. The measurements were carried out at 190 ° C under a nitrogen atmosphere. The measurement indicates the storage modulus (G ') and the loss modulus (G'') together with the absolute value of the complex viscosity (η *) as a function of frequency (ω) or the absolute value of the complex modulus (G *) η * = ((G ' 2 + G '' 2 ) / Ω) 1.2 G * = (G ' 2 + (G ' 2 + G '' 2 ) 1.2

in the inventive method is the viscosity at low shear rates (0.05 rad / s) versus high viscosity Shear rates (300 rad / s) graphically as a feature of processability applied; a high viscosity at low shear rates in conjunction with a low viscosity at high Shear rates provide excellent processability.

example 1

134 g of a metallocene complex (bis (n-butyldicyclopentadienyl) hafnium dichloride, supplied by Witco as TA02823, contains 0.36 wt% Hf) and 9.67 kg of a 30% solution of methylalumoxane (MAO) in toluene (supplied by Albemarle) 3.18 kg of dry, purified toluene were added. The complex solution thus obtained became very slow, even spraying within two hours to 17 kg of the silica support Sylopol 55 SJ (supplied by Grace). The temperature was below 30 ° C held. The mixture was allowed to become three after the addition of the complex Hours at 30 ° C react.

Example 2

Polymer A

A continuous closed-loop reactor with a volume of 500 dm ³ was operated at a temperature of 85 ° C and a pressure of 60 bar. Into the reactor, the diluent propane, ethylene, comonomer 1-butene, hydrogen and the polymerization catalyst described in Example 1 were introduced in such amounts that the ethylene concentration in the liquid phase of the closed-loop reactor was 5.8 mol% Ratio of hydrogen to ethylene at 0.48 mol / kmol was, the ratio between 1-butene and ethylene 118 mol / kmol and the polymer production rate in the reactor was 30 kg / h. The polymer thus produced had a melt index MFR ₂ of 79 g / 10 min and a density of 938 kg / m ³ .

The Suspension was immediately withdrawn from the reactor using a settling strand was used, and passed to a flash tank, which at a Temperature of about 50 ° C and a pressure of about 3 bar was operated.

Out the relaxation tank was the polymer powder containing a small amount of residual hydrocarbons contained in a gas phase reactor at a temperature of 75 ° C and a pressure of 20 bar was operated. In the gas phase reactor were also further ethylene, the comonomer 1-hexene and nitrogen introduced as an inert gas in such amounts that the ethylene concentration in the recycle gas was 37 mol%, the ratio between 1-hexene and Ethylene was 10 mol / kmol and the polymer production rate 37 kg / h amounted to. The concentration of 1-butene and hydrogen was so low that she could not be detected by the direct chromatograph, the was used to monitor the gas composition.

The polymer captured from the gas phase reactor was stabilized, by adding to the powder 0.15% by weight of stabilizer, Irganox B561 were. Then the stabilized polymer was extruded CIM90P extruded and granulated, manufactured by Japan Steel Works becomes.

The distribution of production between the closed loop reactor and the gas phase reactor was consequently 45/55. The polymer granules had a melt index MFR ² of 0.78 g / 10 min, a density of 919 kg / m ³ , a content of 1-butene of 1.4 wt%, a content of 1-hexene of 7.1 % By weight, a weight average molecular weight M _w of 131,000 g / mol, a number average molecular weight M _n of 28,200 g / mol and a z-average molecular weight M _z of 333,000 g / mol. In addition, the polymer had a viscosity at a shear rate of zero η ₀ of 11,700 Pa · s and a _{shear thinning index} SHI _0/100 of 3.9.

Example 3

Polymer B

The The procedure of Example 2 was repeated except that the process conditions as set out in Table 1.

• * bedeutet, daß der Wert zu niedrig war, um ihn durch GC zu erfassen

The polymer granules had a melt index MFR ₂ of 0.76 g / 10 min, a density of 919 kg / m ³ , a content of 1-butene of 2.0 wt%, a content of 1-hexene of 6.8 % By weight, a weight average molecular weight M _w of 126,000 g / mol, a number average molecular weight M _n of 16,600 g / mol and a z-average molecular weight M _z of 349,000 g / mol. In addition, the polymer had a viscosity at a shear rate of zero η ₀ of 12,900 Pa · s and a _{shear thinning index} SHI _0/100 of 5.4. Table 1

• * means that the value was too low to be detected by GC

The Properties of the polymers of Examples 2, 3 and 6 are in the listed in Table 2 below.

Table 2

Example 4

film production

With the polymers of Examples 2 and 3 and as a comparison (C) a LDPE (FT5230 from Borealis A / S), (D) a bimodal ZN-LLDPE with Butene-1 as comonomer (FB2230 from Borealis), (E) a ZN-LLDPE with butene-1 as a comonomer (FG 5190 from Borealis A / S) and (F) an SSC-PE with Octen-1 as comonomer (Elite 5400 from DOW) was used on a Reifenhauser film unit with a nozzle diameter of 150 mm, a screw diameter of 70 mm, a BUR (blow ratio) of 2.5: 1 at a nozzle gap of 2.0 mm and a nozzle temperature of 210 ° C Extruded films to a thickness of 40 microns.

The hot tack of the films was measured and is in 1 shown graphically. As can be seen, the films of the present invention are comparable to and superior to those using PE with octene as a comonomer, using lower α-olefin comonomers.

Example 5

polymer blend

The polymer mixture of Example 3 was mixed with 4% by weight of LDPE produced in an autoclave (FA 5223 from Borealis A / S, MFR ₂ = 1.2 g / 10 min, density 922 kg / m ³ ) or 4 wt. -% of a mixed generated in the autoclave LDPE (CA 8200 from Borealis a / S, MFR ₂ = 7.5 g / 10 min, density 920 kg / m ^3). The resulting mixtures, the polymers (G) and (H), respectively, and the polymer B itself were made into films having a thickness of 40 μm using a Ankutec film blowing device, 30 mm, LD ratio 25: 1, nozzle diameter 50 mm, nozzle gap 2.4 mm. The gloss and haze were determined by ASTM D2457 and ASTM D 1003, respectively, and the results are shown in Table 3 below:

Table 3

The Polymer of Example 6 became similar 4% by weight FA5223 or 4% by weight tubular or tubular LDPE with a relatively high density (FA5270 from Borealis A / S) or with 4 wt.% CA8200 mixed. The resulting mixtures, the polymers (I), (J) and (K) were in similar Way blown, and the turbidity and the shine became more similar Way determined. The results are in the table below 4 listed:

Table 4

Example 6

Polymer L

The The procedure of Example 2 was repeated except that the process conditions as set out in Table 1.

The polymer granules had a melt index MFR ₂ of 0.86 g / 10 min, a density of 919 kg / m ³ , a content of 1-butene of 1.5 wt%, a content of 1-hexene of 7.3 % By weight, a weight average molecular weight M _w of 127,000 g / mol, a number average molecular weight M _n of 22,200 g / mol and a z-average molecular weight M _z of 324,000 g / mol. In addition, the polymer had a viscosity at a shear rate of zero η ₀ of 11,000 Pa · s and a _{shear thinning index} SHT _0/100 of 4.

Claims (21)

Polyethylene film produced by a polymerization catalyzed by a uniform active site catalyst having more than one η ⁵ -cyclic ligand and containing as comonomers for ethylene at least two C _4-12 α-olefins includes. A film according to claim 1, wherein said comonomers are Butene-1, hexene-1, 4-methylpentene-1, heptene-1, octene-1 and decene-1 selected are. A film according to claim 2, wherein the comonomers are butene-1 and witches-1 are. A film according to any one of claims 1 to 3, wherein the polyethylene is a bimodal polyethylene, the component having lower Molecular weight 30 to 70 wt .-% of the polyethylene. A film according to any one of claims 1 to 4, wherein the comonomer content of the polyethylene is 0.1 to 10 mol%. A film according to any one of claims 1 to 5, wherein the density of the polyethylene is 905 to 930 kg / m ³ . A film according to any one of claims 1 to 6, wherein the weight average the molecular weight of the polyethylene 50,000 to 250,000 g / mol is. A film according to any one of claims 1 to 7, wherein the molecular weight distribution of the polyethylene is 3 to 8. A film according to any one of claims 1 to 8, wherein the MFR ₂ value of the polyethylene is 0.4 to 3 g / 10 min. A film according to any one of claims 1 to 9, wherein the polyethylene mixed with another polymer. The film of claim 10, wherein the further polymer is a low density polyethylene (LDPE). A film according to any one of claims 1 to 11, which is a plurality of layers. A film according to any one of claims 1 to 12, obtained by extrusion at a blow-up ratio from 2: 1 to 4: 1. A polyethylene composition for film making, the composition comprising a polyethylene made by a polymerization catalyzed by a uniform active site catalyst having more than one η ⁵ -cyclic ligand, and as comonomers for ethylene at least two C _4-12 alpha-olefins. A composition according to claim 14, which is a polyethylene according to one of the claims 2 to 9. A composition according to any one of claims 14 and 15, which is a mixture of this polyethylene and another polymer includes. A composition according to claim 16, wherein said further Polymer is a low density polyethylene (LDPE). A product packaged in a heat-sealing film of a polyethylene prepared by a polymerization catalyzed by a single site catalyst having more than one η ⁵ -cyclic ligand, and as comonomers for ethylene at least two C _4-12 alpha-olefins. A product according to claim 18, wherein the film is as in one of the claims 2 to 13 is indicated. Product according to one of claims 18 and 19, which is a packaged Food or a packaged liquid is. Use of LDPE at a density of 925 to 932 kg / m ³ as an additive present at 1 to 5% by weight in a polyethylene composition for film production to improve the optical properties of the film made therefrom.